In a magnetic recording/reproducing device such as a tape drive having a rotary head assembly, the magnetic heads are mounted adjacent to the outer periphery of the rotating position of the drum (hereinafter “rotor”) so that the heads can scan a flexible, magnetic tape as the latter is disposed adjacent to and moves along a portion of the path of travel of the heads.
In the prior art the rotor which mounts the heads has a transformer at the center thereof so that the data signals sensed by the heads during a read mode can be directed to circuitry which is external to the rotary head assembly itself. Also, for a record mode, the transformer interconnects the data signal source with at least one of the heads. In either mode, the head or heads are connected directly to the transformer.
The foregoing practice presents a noise and signal distortion problem due to the separation of the amplifier circuitry from the heads. Such noise is added to the data signal from the heads in a read mode and amplified in the circuitry external to the rotor.
Accordingly, movement is being made in the industry from the above prior art rotor assembly to a rotor assembly having a number of heads mounted thereon and having amplifier means coupling each head, respectively, with the transformer. In this way, the data signals sensed by the heads during a read mode are amplified before being directed to the transformer. Thus, any noise generated by the transformer itself will represent only a relatively small fraction of the signal transferred by the transformer to the electronic circuitry externally of the drum assembly. The signal-to-noise ratio of the data signals, therefore, is relatively high.
In a similar manner, the head assembly can also include a write signal amplifier mounted on the rotor along with the read signal amplifiers for the heads. Thus, data signals to be recorded need not be amplified until they have passed through the transformer to thereby assure fast current rise times needed for recording at higher flux densities.
While the repositioning of the readback and recording amplifiers and other associated electronics (e.g., control circuitry) within the rotor of the drum itself is desirable for the reasons set forth above, several difficulties exist with the implementation of such a design. Foremost is the development of a control interface between the stationary drive electronics and the rotating rotor electronics to allow control thereof. Noise generated by the rotating drum often causes control signal transmission errors or dropouts, resulting in control command misinterpretation, thereby setting the rotating control electronics to perform unintended operations.
Accordingly, a control interface is needed to allow accurate communication between control electronics situated on the stationary tape drive electronics and the rotating drum electronics to allow signals generated by the controller and needed by the drum electronics to function to be sent with as much accuracy and speed as possible. Preferably, the interface is implemented using as few control channels as possible.